Piston-expanding means



Jan. 28, 1930. F. E. vcowLE 1,745,336

PIs'ToN EXPANDING MEANS Filed Oct. 25, 1926 Fma 5 FIG. 4

INVENTOR.

FREDERICK E COWLE y BY A T T ORNEY Patented Jan. 28, 193i) uNirEn ras Para Nr orFrca vBREIDERCK E. COWLE; OF SAN DIEGO CALIFORNIA, AISSIGNOR O`F` ONELTHIRD T0 DAVE) S. BONE' AND ONEiTI-IIRD yTU JOHN WI CIO'OIEY,` BOTH 0F' SAN DIEGO, CA11- PISTONLEXPANDING MEA-.NS-

i Application filed October' 25,` 1926. Serial Nb; 1442095.

length. ot the cylindrical body undergoing expansion ,ctl'ii-rd, tolprovide' a tool offtheclass described which may be insertedI within a hol"- low cylindrical body, having bosses -orsi'mi'l'ar protuberances: on itsf inner surface:

With these andA5 other objectsiin-viewf, aswill appearl hereinafter, my invention consists 'of'cert'alininovel featuresof constructi'on,,comv` "hrnati'on and arrangement o-f'parts, aslwill be hereinafter described inl detail and particularly'set forth inthe: appended claims, reference beingjhadl tfolt'her accompanying drawings and to-t`he characters of` reference thereon, which form a part; of thisapplication, in which :4

Figure 1T is a front elevational view of'the device, partly in section andi showing-'the deviceapplie'd to a piston, sliown in dotted lines; 'Figi 2 isf aplanl view' inA section through the line;Qf-2" inl Fig, 1 Fig; Slisl a sid'eelevational view off the device, the expansion screw being sli'ownfin" part only, andE Fig. 4 i'saplan view in which thel expansion screwf and two of'the cover' plate screwsl areI shown in section.`

Like reference characters refer to' simil-lar parts' andportions throughout the several viewsfofthe drawings.

rFhe principal parts of'mypiston expanding device are thetapered core member 1f, the-sew eral annular, segmental dies' or quarter sections 2, 3, i andi 5,'the expansion screw 6, cover plate 7 and cover plate screws 83, 9,10 and Il'. These partsl' prefer to make'- of steel. VThe ytapered core member l is in form a f'rust'um of right circular cone, and is bored ythrough axially and provided with' internal "screw threads la. The sections'', 3, 4 and 5 form together substantially a hollow cylindrical die, as shown in Fig. 2', their outer surfaces forming al cylinder when-,the sections are grouped together, whiletheinner surfaces 'form an axialllyextending, tapered, circular opening corresponding to the taperv of the core member l. The lower ends of thesections are cut away inlpart, forming'a rectangular channel extending transversely' across thebottomiend ofthe dica-nd axially approximately twokt'hird's' the length of' the die', the side surfaces limiting this channel' being represented by theI qua-rter section surfaces EZ, 85, 4a' and? 5?and the upper surfaces-2b, 3- '41 andi 5", as showni'nfFigs.` 2 and 31. As' clearly illustrated in Fig. 1, theobject ofthi's channel is to'provide clearance for the bosses l2 and 1Q in the piston l2; shownA in dotted lines. The upper' endsY of the several quarter sections form an annular, axially extending rim, with-innersurfaces-Z", 3c, 4 and 5F, which serveV toremhracethe'outer cylindrical surface of the' cover platea?.

The` expansion screw"I member 6? comprises a5 bar having'l a. lower" threaded portipn- @suit-'- able forscrewing into-the core,member=1, an unthreaded upper portion 6P, provided with a removable crossbar 13 at the top end, for enabling the exertion of' considerable-manual force on-v tle screw member 6, and a narrow annular-collar 6", preferablyforming a-nintegral partv of the sazid bar, located between t'lJ'e threaded and unthreaded portions there'- o The cover plate? is av strong circular plate provided with a centrally located, circular openinglsaid opening beingcounterboredto a depth of about half thel thickness of the plate toadia-meterA somewhat greaterI than that of the collar 6c, and forming within theplate 7' an annular seating f@against which the upper surface of said collary rests, while the bar portion 6b ofthe expansion screw 6 is4 free to passfthrough the opening; Thecrossbar 13 is, of course, removed until the parts are assembled. The cover-plate 7 is provided with aplurality of radially elongatedslots 13, 14, 15 and l'through Which'theabolts 8, 9, 10' and l'l are free to pass, said bolts being screwed into' suitably threaded holes, not shown, in the quarter sections 2, 3, 4 and 5; The bolts 8, 9; lOandll' are-so positioned; when the quarter sections are grouped to formI a complete cylinder that they occupy' the innery ends' ofv the slots 13 and 154:,while the'cover, plate is registered by the annular rim formed by the surfaces 2`", 3, 4:6 and 5 of' thev quarterA sections.

In Fig. 1 the device is shown inits as'- sembled form, placed within the piston 12. The latter is shown with surface grooves or splits 12C, which it is customary to provide in pistons for facilitating expansion and contraction due to heating during normal operation. rIhe core 1 is shown in a position close to the cover plate 7. In this position the dies 2, 3, 4 and 5 ,are an easy fit within the piston, the wrist pin bosses 12a and 12b of the latter` occupying the rectangular channel as previously explained. By revolving the expansion screw 6, the core 1 may be forced downwardly within the dies 2, 3,74 and v5, forcing them outwardly. The upward thrust on the expansion screw 6 is taken by the collar 6 and the annular seating 7a in the cover plate 7. It will be understoodthat, due to the very great leverage obtained by this construction, a considerable radial expanding force may be exerted upon the inner surfaces of the piston. The radial outward movement of the dies 2, 3, 4 and 5, in consequence of the downward movement of the core 1, causes the screws 8, 9, 10 and 11 to be displaced outwardly, the elongated slots 13a, 14, 15 and 16 in the cover plate 7 through which they pass,

pressing fit with the interiorl piston surface.k

I then heat the piston and tool to a temperature of from 400 to 800 degrees Fahrenheit. While at this temperature, I expand the piston by means of the expansion tool. At this temperature I have found that the metal takes on a permanent set, so that after allowing the, piston to cool somewhatand removing the tool,.the outer diameterof thepiston will have increased considerably. It is then possible to refinish Y the outer surface to a greater diameter than that of the untreated piston.

In the case of pistons having no splits in their outer surface, I prefer to first split the piston similarly to the conventional split surface piston, then proceed in the manner as above set forth. y

It is clear that inthe process I have described, I bring about the permanent expansion of the piston by bringing the temperature of the metal Vto a critical value at which the inherent elasticity is greatly reduced. By subjecting the walls of the piston to relatively great radial pressure, evenly distributed over their surface, I am able to increase the peripheries of the said walls; that is, the diameter of the piston which occurs while the metal is still at the above mentioned critical temperature. Thus, when surface.

the metal is allowed to cool while restrained by means of the expansion tool, it does not again contract. The process, however, does -clude V,in the scope ofjmy invention the construction substantially as set forth in the appended claims.

Having thus described my invention, what I claim as newand desire to secure by Letters Patent is:

1. In a device of the class described, a hollow, internally threaded tapered core member, a plurality ofV annular segmental dies forming together a substantially cylindrical outer surface and an axially extending tapered Opening capable of receiving said core member in intimate surface contact and forming also a transverse, axially extending channel, rotatably screwably mounted means adapted to fit in said hollow, internally threaded portion of said core member for forcing said core member axially with respect to the said dies, and further means for restraining said longitudinal forcing means from other than rotary movement.

2. In a device of the class described, a tapered core member, a plurality of annular segmental dies, their outer surfacesforming together a substantially cylindrical surface, their inner surfaces forming a tapered, axially extending opening capable of receiving said core member in intimate surface -contact and forming also a transverse channel permitting passage of said dies over protuberances extending within the connes of said cylindrical outer surface,'and means for forcibly moving said core member in an axial direction within saidsegmental dies.

3. In a device of the class described, a

tapered core member having va jthreaded,

vably secured, said cover plate having a central opening through which the expansion bar is free to pass, and a collar integral with said expansion bar located between the upper core member surface and lower cover plate 4.y In a device of theclass described, a

hollow, internally threaded, tapered core member, a plurality of annular segmental dies, their outer surfaces forming together a substantially cylindrical surface, ytheir inner surfaces forming a tapered axially extending opening Capable of receiving said core member in intimate surface Contact and vforming also ay transverse channel permit- FREDERICK E. COWLE. 

